ethereum(以太坊)(七)--枚举/映射/构造函数/修改器

pragma solidity ^0.4.10;
 
//枚举类型
contract enumTest{
    enum ActionChoices{Left,Right,Straight,Still}
                    //  0    1       2       3
    //input/output  uint
    ActionChoices public _choice;
    ActionChoices defaultChoice = ActionChoices.Straight;
 
    function setStraight(ActionChoices choice) public{
        _choice = choice;
    }
    function getDefaultChoice() constant public returns(uint){
        return uint(defaultChoice); //
    }
    function isLeft(ActionChoices choice) constant public returns(bool){
        if (choice == ActionChoices.Left){
            return true; //
        }
        return false; //1,2,3
    }
}
//构造函数
contract StructTest{
    struct Student{
        string name;
        uint sex;
        uint age;
        //uint year =15;ParserError: Expected ';' but got '=':Cannot be assigned within the constructor,unless use constructor public{}
    }
 
    Student public std1 = Student('lily',0,15);
    Student public std2 = Student({name:'lin',sex:1,age:17});
    /*
    0: string: name lin
    1: uint256: sex 1
    2: uint256: age 17
    */
 
    Student [] public students;
 
    function assgin() public{
        students.push(std1);
        students.push(std2);
        std1.name ='eilinge';
        /*
        0: string: name eilinge
        1: uint256: sex 0
        2: uint256: age 15
        */
    }
}
 
//映射/字典
contract mappingTest{
    mapping(uint => string) id_names;
 
    /*
    mapping (_key => _values)
    键的类型允许除映射外的所有类型,如数组、合约、枚举、结构体.值的类型无限制.
    映射可以被视作一个哈希表,其中所有可能的键已被虚拟化的创建,被映射到一个默认值(二进制表示的零)
    在映射表中,我们并不存储建的数据,仅仅储存它的keccak256哈希值,用来查找值时使用。
    映射类型,仅能用来定义状态变量,或者是在内部函数中作为storage类型的引用
    */
    constructor() public{
        id_names[0x001] = 'jim';//构造函数内声明的全局变量,任意函数都可以进行调用
        id_names[0x002] = 'eilin';
    }
 
    function getNamebyId(uint id) constant public returns(string){
        string name = id_names[id]; //局部变量 name,仅能在本函数内使用,其他函数无法进行调用
        return name;
    }
}
 
//修改器
pragma solidity ^0.4.10;
 
contract modifierTest{
    address owner=msg.sender;
    uint public v3;
 
    modifier onlyowner(address own) {
        require(own == owner);
        _;
    }
    function setv3() onlyowner(msg.sender) {
        v3 = 10;
    }
}